PROJECT SUMMARY Cancer survival rates are increasing dramatically as novel early diagnostics and new treatments emerge. However, there is a great cost in the form of acute and chronic pain that chemotherapy patients experience immediately after and for many years following successful treatment. As chemotherapy drugs travel throughout the body to target and destroy cancer cells, they severely damage other organs, including nerves, leading to a condition known as chemotherapy-induced peripheral neuropathy (CIPN). Symptoms often appear minutes to hours after the treatment and include pain in the arms and hands, burning or tingling, loss of sensation to touch, difficulties in performing common routines, cramping, constipation, muscle weakness, and balance problems. The search for a treatment for CIPN is one of the major challenges in current oncology practice, with the identification of new agents to prevent and/or treat CIPN being a top priority and long-term objective. Unfortunately, no methods are currently available to assess the extent of CIPN or predict outcomes. Identification of specific biological mechanisms underlying the manifestation of painful CIPN requires a diagnostic tool to monitor CIPN in living subjects to identify a potential therapeutic target. It has been proposed that damaging radicals known as reactive oxygen and nitrogen species (ROS/RNS) cause nerve tissue injury and play a critical role in neurodegenerative diseases. To test this mechanism in living animals, we propose to investigate the spatial, temporal, and interventional aspects of the ROS response to chemotherapy in CIPN animal models and correlate the in vivo imaging results with disease progression. We will be focusing on the mechanism that is related to the burst of ROS, and the repetitive damage in the nerve tissue assessed by the proposed selected markers of chronic CIPN. In the Aim 1 we will first demonstrate that the repetitive stimulation of ROS pathway in mice leads to the symptoms associated with CIPN. After establishing this link, will demonstrate in Aim 2 that the other chemotherapy drugs such as paclitaxel and bortezomib that act with different cytotoxic mechanisms but show similar CIPN behavior follow the same mechanistic pathway. Finally, in Aim 3 we will test our hypothesis in syngeneic and patient-derived xenograft breast cancer models by demonstrating that pharmacological intervention using FDA-approved drugs will minimize ROS and chronic CIPN while not undercutting treatment efficacy. This strategy of combined imaging, histological, biochemical and behavioral methods will lead to identification of the molecular roots of chronic pain in living animals, providing mechanistic insight into the pathogenesis of CIPN. Overall, the outline proposal will enable us to correlate the acute form with chronic CIPN and explore several image-guided strategies to minimize CIPN.